Turbine with internal blades

ABSTRACT

A turbine for pumping a fluid includes a body designed to move rotationally, a hollow central part which extends through the body from one side to the other and is intended to allow the fluid to pass through the turbine, and at least one blade that is positioned on the inner wall of the body, in the hollow central part, and is designed to circulate the fluid.

The present invention relates to a turbine for pumping a fluid, inparticular but not exclusively a pump for ventricular assistance. Theturbine according to the present invention can be used in any system forpumping a fluid.

A turbine according to the invention is a rotary device intended topropel a fluid such as blood or water using energy provided by a motor.

Document WO2017032510 is known, describing a pump equipped with aturbine in an ogive shape. This turbine is equipped with several bladesproduced on the surface thereof. Despite good performance in operation,such a turbine nevertheless has several drawbacks, like weight and thelack of space for the circulation of the fluid.

The purpose of the present invention is a new turbine reducing thestress on the blood cells.

Another purpose of the invention is to limit friction between the fluidand the turbine.

Yet another purpose of the invention is to reduce the energy consumptionof the motor controlling the turbine.

At least one of these objectives is achieved with a turbine for pumpinga fluid, in particular a turbine used for increasing the pressure of thefluid in a pump, this turbine sometimes being referred to as an“impeller”.

According to the invention, this turbine comprises:

-   -   a body designed to perform rotational movements,    -   a hollow central part, passing right through the body and        intended for the passage of fluid through the turbine, and    -   at least one blade arranged on the inner wall of the body, in        the hollow central part, and designed to cause the fluid to        flow.

The object according to the invention is a turbine of a new type, as itis hollow and has internal blades, i.e. directed towards the centralaxis of rotation. In fact, unlike the known turbines or rotors thatgenerally have a main body with blades arranged on the outer surface,the present invention proposes a hollow turbine with blades produced inthe inner surface thereof. The fluid is conveyed through the turbine, onthe inside thereof, directly, in a linear flow, with a minimum offriction.

Such an architecture makes it possible to reduce the weight of theturbine with respect to a solid turbine. This makes it possible toimprove the comfort of a patient when the turbine is installed in acardiac pump for example. Furthermore, the electricity consumption isalso improved due to the low weight. This results in more compactdimensions of the energy source and/or an improved lifetime for anysystem using such a turbine.

As the fluid passes inside the turbine, the flow resistance is reduced.

Stress on the blood cells i.e. the shear forces (shear stress), when thefluid is blood, is considerably reduced. Damage to the blood isconsequently reduced.

According to an advantageous characteristic of the invention, the bladeis of helical type. The function of such a blade is to aspirate thefluid and to make it pass through the inside of the turbine.

This blade can be more or less pronounced, i.e. it can be one or moreattached pieces with respect to the turbine or protrusions, grooves orcorrugations forming an integral part of the turbine, produced on theinner wall thereof.

The helical blade is like a coil on the inner wall of the turbine, sothat the angle of incidence of the helical blade reduces from theupstream end to the downstream end of the turbine; the angle ofincidence being defined as the angle between the axis of rotation of theturbine and a vector tangent to the outer surface of the helical blade.

According to another advantageous characteristic of the invention, theturbine comprises several blades distributed on the inner wall of saidbody. These blades are arranged to apply a minimum of stress to thefluid and to optimize aspiration.

According to an embodiment of the invention, the blade is constituted byseveral turns with an increasing winding pitch that tends towardsinfinity.

In an embodiment, the turbine according to the invention can comprise arod arranged along the central axis so as to reduce the backflow offluid.

The rod can advantageously be fixed. Although this does not constitute apreferred embodiment, it is nevertheless possible to envisage a rotatingrod, firmly fixed to the turbine or not, fixed to the inlet chamber ornot.

For example, this rod can be fixed to said at least one blade or to thebody of the turbine or by one end to an inlet chamber which can befirmly fixed to a casing around the turbine. When the rod is fixed tothe inlet chamber, it is fixed and the turbine can revolve about it.

The function of this rod is to contribute to stopping any reflux ofblood and preventing the creation of vortices.

Advantageously, the hollow central part of the turbine can have acylindrical shape. That is to say that the inner wall of the turbine canhave the profile of a right cylinder, with a circular cross section forexample, and/or the fixed or variable radial thickness of the blade issuch that the void (filled with air or fluid) has the profile of a rightcylinder, with a circular cross section for example.

According to an embodiment of the invention, the hollow central part canhave a flared shape, the more open end being arranged downstream in thedirection of flow of the fluid.

The outlet orifice of the turbine is larger than the inlet orifice.

According to another embodiment of the invention, the hollow centralpart of the turbine has an oblong shape, the more open end beingarranged downstream in the direction of flow of the fluid.

Preferably, for efficient rotation, the body of the turbine can have anouter shape of the right cylinder type with a circular cross section.

Advantageously, permanent magnets can be incorporated into said body.These magnets make it possible to use the turbine as the rotor of anasynchronous motor, for example.

According to an embodiment, the radial thickness of the blade can befixed or variable over the entire length between the upstream end andthe downstream end of this blade, i.e. over the entire length of theblade. If it remains constant, the blades then delimit a zone which hasa shape substantially identical to the shape of the hollow part.

According to an advantageous characteristic of the invention, the hollowcentral part and said at least one blade having a profile of centrifugaltype on the upstream side, mixed-flow type in the central part, andaxial type on the downstream side.

With the pump according to the invention, the turbine is capable ofproviding a pump incorporating at the same time the characteristics of:

-   -   a pump of centrifugal type, i.e. radial acceleration for the        portion of the fluid caught by the blades and arriving axially;        to this end, the lower part of the blades, in particular        helical, can have a pronounced angle, of the order of 45        degrees, for example between 40 and 50 degrees, with respect to        the axis of rotation of the turbine,    -   a pump of mixed-flow type, i.e. a less pronounced slope or curve        of the turns of the helical blades for example, and    -   a pump of axial type, the fluid being channelled in a direction        parallel to the axis of rotation of the turbine.

This configuration makes it possible to limit the shear stress which cancause hemolysis, i.e. destruction of the red blood cells. Even with ahigh flow rate, when red blood cells are destroyed, oxygen does notreach the cells.

Shear stresses are created by the effects of blood swirling at the inletand outlet of the pump. The pump according to the invention avoidsvortices via suction of blood using a structure of the centrifugal typeand an axial delivery.

According to an advantageous characteristic of the invention, a firstzone of said at least one blade is dimensioned so that the fluid reachesa specific speed comprised between 0 and 1.2; this first zone being onthe upstream side of the blade.

Furthermore, a second zone of said at least one blade is dimensioned sothat the fluid reaches a specific speed comprised between 1 and 2.2;this second zone being at the level of the middle of the blade.

Finally, a third zone of said at least one blade is dimensioned so thatthe fluid can reach a specific speed greater than 2.2; this second zonebeing on the downstream side of the blade. This is a specific speedvalue making it possible to classify the centrifugal, mixed-flow oraxial structures respectively.

According to another aspect of the invention, a pump is proposed,designed for the circulation of a fluid, this pump comprising:

-   -   a casing, and    -   a turbine arranged in the casing and designed to perform        rotational movements relative to the casing.

According to the invention, the turbine comprises:

-   -   a body designed to perform rotational movements,    -   a hollow central part, passing right through the body and        intended for the passage of fluid through the turbine, and    -   at least one blade arranged on the inner wall of the body, in        the hollow central part, and designed to cause the fluid to        flow.

The pump according to the invention incorporates the new turbinedescribed above, thus benefiting from the advantages established forthis turbine. The pump according to the invention can also operate witha very low noise level.

Advantageously, the casing and the turbine can constitute a part of abrushless motor, the casing having the stator function and the turbinehaving the rotor function. Thus a synchronous machine is constituted,with permanent magnets arranged in the rotor, while stator coils(windings) are produced in the casing used as stator. In thisembodiment, the control electronics is provided and arranged in such away as to act on the windings.

According to another embodiment of the invention, the pump can comprisea motor external to the turbine and driving a transmission shaft, thelatter being arranged along the axis of rotation of the turbine andfirmly connected to the turbine by at least one radial rib. Unlike thepreceding case where the motor was finally incorporated, in the presentembodiment, the motor is external to the turbine and comprises a shaftwhich drives the turbine in rotation. The shaft is firmly fixed to theturbine by ribs which have a profile allowing easy passage of the fluid.

Preferably, the transmission shaft can be connected at both the upstreamend and the downstream end of the blade.

According to an advantageous characteristic of the invention, the pumpalso comprises:

-   -   an inductor equipped with guide vanes to make the flow of the        fluid linear; this inductor being arranged upstream of the        turbine with respect to the direction of flow of the fluid;    -   a diffuser equipped with diffusion vanes in order to make the        flow of fluid linear and increase the pressure of the fluid;        this diffuser being arranged downstream of the turbine so as to        evacuate the fluid outwards from the turbine, converting the        kinetic energy created by the turbine into potential energy; and    -   a straightener equipped with straightener vanes and an outlet        orifice having a diameter less than the inlet diameter of the        straightener, the straightener vanes directing the fluid from        the diffuser to the orifice so as to increase the speed and give        the fluid a predefined profile when leaving the orifice.

The linear flow of fluid such as defined here is linear by comparisonwith a swirling flow. This linear flow can be laminar.

The straightener according to the invention makes it possible to createa flow by concentrating the fluid so as to obtain high speed values atthe outlet of the pump. In general, the vascular system of a heart hasfairly high circulatory resistances. An efficient pump is a pump that iscapable of propelling the blood in the valves with sufficient pressureto overcome these circulatory resistances. The pump outlet pressure isparamount in comparison to the outlet speed, which with the pumpaccording to the invention can reach the maximum speed of 3 m/s.

In other words, the straightener makes it possible to channel the fluid,to create a profile making it possible to have a maximum speed at apoint, i.e. aligned with the aortic valve, so as to expel the flow in alaminar fashion. This makes it possible to avoid the creation ofvortices at the outlet of the pump. The diameter of the outlet orificeis smaller than the internal diameter of the casing. The smaller outletdiameter thereof, for example half or a third of the internal diameterof the casing, makes it possible to adjust the pressure parameters,between 80 and 200 mmHg, and the speed parameters, between 1 and 3 m/s,while avoiding the creation of a flow with negative speed (backflow dueto lack of pressure and homogeneity of the outlet flow).

The diffuser and straightener assembly according to the invention thusmakes it possible for the pump to be made efficient. The straightenerdistributes the fluid directly towards the outlet in the ambient mediumby creating a flow therein. This ambient medium can advantageously besaid fluid, which is preferably blood.

The inductor according to the invention avoids the phenomenon ofcavitation, i.e. the creation of vapour bubbles in the fluid.

It is important to note that this pump is perfectly suitable foroperation in a vertical arrangement, or slanting slightly, i.e. inclinedbetween 0 and 5 degrees with respect to the vertical axis. The pumpaccording to the invention can also operate lying down, like most of thepumps of the prior art.

The pump according to the invention can also comprise an inlet chamberequipped with side openings so that the fluid can enter radially thenengage axially towards the inductor. This inlet chamber can have acylindrical shape comprising, on its upper part downstream of saidopenings, a receptacle for housing the inductor. The inlet chamber andthe inductor can constitute two parts intended to be firmly fixed to oneanother or be designed as one and the same piece. The casing can also becombined with them so as to constitute a single piece.

Other advantages and characteristics of the invention will becomeapparent on examination of the detailed description of an embodimentthat is in no way limitative and from the attached drawings, in which:

FIG. 1 is a diagrammatic view of a turbine with internal bladesaccording to the invention,

FIGS. 2a, 2b and 2c are diagrams showing the arrangement of the helicalblades inside the turbine according to the invention,

FIGS. 3a, 3b and 3c are diagrammatic cross section views showing abrushless DC motor in different configurations of the hollow centralpart of the turbine according to the invention,

FIG. 3d is a diagrammatic cross section view showing a motor of the typeof those set out in FIGS. 3a to 3c with a rod arranged at the centre ofthe turbine,

FIG. 3e is a diagrammatic view of an inlet chamber bearing the rod inFIG. 3 d,

FIG. 4 is a transparent diagrammatic view of the inside of a pumpincorporating a turbine according to the invention,

FIG. 5 is an exploded view of the pump incorporating a turbine accordingto the invention,

FIG. 6 is a view in cross section of the pump in FIGS. 4 and 5,

FIG. 7 is a longitudinal diagrammatic view in cross section of a pumpaccording to the invention,

FIG. 8 is a perspective view of an inlet chamber according to theinvention,

FIG. 9 is a perspective view of an inductor to be inserted in the inletchamber according to the invention,

FIG. 10 shows different views in cross section and in perspective of acasing intended to contain the turbine according to the invention,

FIG. 11 is a perspective view of a diffuser according to the invention,

FIG. 12 is a perspective view of a straightener according to theinvention,

FIG. 13 is a perspective view of a turbine fixed to a transmission shaftof a motor according to the invention,

FIG. 14 is an exploded view of the pump incorporating the turbine inFIG. 13 according to the invention,

FIG. 15 is a diagrammatic view showing a fastening between atransmission shaft and the turbine in FIG. 13 according to theinvention,

FIG. 16 is a diagrammatic cross section view exposing the inside of apump incorporating the turbine in FIG. 13 according to the invention,

FIG. 17 is a diagrammatic view of a pump according to the inventioncomprising a motor the transmission shaft of which is connected to theturbine in FIG. 13 according to the invention,

FIGS. 18 and 19 are diagrammatic views of an inductor according to theinvention, and

FIGS. 20 and 21 are diagrammatic views of a straightener according tothe invention.

The embodiments which will be described hereinafter are in no waylimitative; in particular variants of the invention may be implementedcomprising only a selection of the characteristics describedhereinafter, in isolation from the other characteristics described, ifthis selection of characteristics is sufficient to confer a technicaladvantage or to differentiate the invention with respect to the state ofthe prior art. This selection comprises at least one, preferablyfunctional, characteristic without structural details, or with only apart of the structural details if this part alone is sufficient toconfer a technical advantage or to differentiate the invention withrespect to the state of the prior art.

In particular, all the variants and all the embodiments described areintended to be combined together in any combination, where there is noobjection on technical grounds thereto.

In the figures, elements common to several figures retain the samereference.

FIG. 1 shows a turbine 1 according to the invention. In the example,described non-limitatively, this is a body 2 in the shape of a slenderhollow cylinder the inner wall 3 of which comprises several blades 4, 5,6 and 7. Such a turbine can advantageously be used in a pump immersed ina fluid.

The function of the blades is to convey the fluid through the turbine.The orientation and dimensioning of the blades are provided so that thefluid is aspirated then propelled after having passed through theturbine when in rotation.

Unlike the systems of the prior art where the fluid flows on the outsideof the turbine, the present invention proposes a hollow turbine makingthe fluid flow on the inside.

FIG. 2b shows the four helical blades 4 to 7, which start from one endof the turbine, lie in helical lines without ever crossing one another,and arrive at the other end.

In the example in FIG. 2b , the hollow central part of the body 2 has aconcave flared shape. The upstream end 2 a has a smaller opening thanthe downstream end. FIG. 2a is a front view of the end 2 a while FIG. 2cis a front view of the end 2 c. The helical blades follow the shape ofthe inner wall 3.

The hollow central part can have other shapes like those shownnon-limitatively in FIGS. 3a to 3 c.

A turbine 8 is shown in cross section in FIG. 3a . This is a cylinderhaving a flared hollow central part 8 a shaped like a funnel. A blade 4is shown diagrammatically. Of course, several blades 4, 5, 6 or 7 can bearranged. This turbine 8 is designed to rotate with respect to asurrounding casing 9. Ideally, the casing 9 is a stator comprisingmagnetic windings 10. These latter can work together magnetically withpermanent magnets 11 arranged on the inside or the outer surface of theturbine. Electronic means (not shown) are provided for controlling thewindings 10 so as to actuate the turbine. The assembly constitutes amotor of the brushless type. The gap between the turbine and the casingis straight, it lies within a right cylinder, but it can have anothershape that is not straight, flared or not.

In FIG. 3b , the hollow central part 81 a has an oblong shape as in FIG.2b , but with a slightly closed-in downstream end.

In FIG. 3c , the hollow central part 82 a has the shape of a rightcylinder.

The three FIGS. 3a, 3b and 3c have the same casing 9 as well as the samemagnetic elements allowing a motor of the brushless type to beconstituted.

It has been noted that the arrangement of a rod inside the turbine makesit possible to improve blood flow when the pump is in operation, i.e.the turbine in rotation with respect to the casing. FIG. 3d shows anembodiment of a pump in which a straight rod 88 is axially arranged inthe turbine. In the example shown in FIG. 3d , the pump comprises aninlet chamber 85, 86 which can be seen in FIG. 3e . This inlet chambercomprises a base 85 bearing bridging pieces 86 linked to a ring 89 forfastening to the casing 9. The passages between the ring 89 and the base85 allow the entry 87 of the fluid or the blood towards the inside ofthe turbine along the rod 88, under the action of the blades 4, 5, 6, 7.This rod 88 can have a height such that the free end thereof (upper inFIG. 3d ) is located inside the turbine, beyond the turbine, flush withthe upper end of the turbine or the casing.

The rod 88 is fixed by one end to the base 85. Other arrangements of therod can be envisaged, such as for example connected to the turbine onlyand no longer to the base 85. In fact, the rod 88 can be fixed to thebody 82 of the turbine or to one of the blades 4, 5, 6, 7 for example atthe top, at the upper end (with respect to the representation in FIG. 3d). In this case, the lower end of the rod 88 can preferably be free orfixed to a blade, to the body of the turbine or to the inlet chamber.

In particular, in addition to the above and in a manner compatible withother embodiments, the turbine can be contained within the casing bymeans of flanges 83 and/or 84 produced for example at the ends of thecasing and extending inwards. Roller bearing mechanisms can be providedbetween the turbine and the flanges. Other means can be provided to holdthe turbine in rotation in the casing without contact. In particular, amechanism can be envisaged using levitation, a fluid, magnetism, etc.with or without the flanges 83 and/or 84.

FIGS. 1 to 3 set out in particular a turbine and a casing which,combined with the components for inlet and outlet of fluid andelectronic components, make it possible to constitute a pump.

A pump according to the invention, incorporating a turbine as describedabove, will now be described with reference to FIGS. 4 to 6.

FIG. 4 shows a transparent overall view of a pump 12. This pump has theoverall shape of a cylinder with a circular cross section, intended toaspirate a fluid such as blood and deliver it so as to promote bloodcirculation. Such a pump is intended to be installed in a body, inparticular for ventricular assistance. The length thereof isapproximately 61.8 mm, the diameter of the casing 9 is approximately17-20 mm, while the lower part 13 has a diameter of approximately 15-20mm.

The pump according to the invention can advantageously, but notexclusively, be used in a vertical position, i.e. with the casing 9vertical and above the lower part 13.

According to the invention, the function of the inlet chamber 13 is toallow fluid, in particular blood, to enter via the inlets or openings 13a under the action of aspiration originating from inside the casing 9.The fluid is then delivered via an opening at the upper end of thecasing.

The upper stages of the inlet chamber 13 comprise the turbine 1 intendedto rotate inside the casing 9, and outlet elements such as a diffuser 14and a straightener 15. The turbine 1 shown in the exploded view in FIG.5 has a hollow central part, oblong, oval or ogival in shape, elongatedor extended on one end. The hollow central part delimited by the innerwall 3 has a diameter of the circular cross section (radial section)that increases from the lower part thereof to the upper part.

In FIG. 5, the exploded view makes it possible to understand that thetwo components shown externally overall are the casing 9, having asmaller lower part intended to be inserted into the upper part of theinlet chamber 13. The turbine 1 is inserted inside the casing 9, in thecentral part. The diffuser 14 and the straightener 15 are nested in thecasing 9 by the upper end.

FIG. 6 clearly shows the helical blades produced on the inner wall 3.

The different parts of the pump can be designed for moulding, 3Dprinting, machining, or other means. Advantageously, between three andfive blades are produced.

In FIG. 7, arrows 16 indicate the path of the fluid inside the pump. Thefluid enters via openings 13 a in the inlet chamber, and is then axiallyaccelerated in the turbine under the rotary action of the blades. Eachhelical blade is a coil the thickness of which is constant or variableover the entire length so that the shape of the inner space conforms tothe shape of the inner wall 3, or not. This inner shape is oblong or ofthe ogival type.

The axial turbine according to the invention is provided for continuousoperation.

Fluid circulation takes place in a linear flow which occupies the entirecentral space of the turbine. The flow rate is thus significant, and inparticular when it is blood, the fluid undergoes the smallest possibleimpact, therefore the least possible stress on the cells.

FIG. 8 shows the inlet chamber 13 in greater detail, constituted by alower part 13 b, an upper part 13 c, the two parts being connected byradial guides 13 d delimiting the openings 13 a towards the inside ofthe inlet chamber.

The lower part 13 b is a cylinder with a circular cross section, havinga thick wall, such that the central part is a tunnel 13 e. In theexample in FIG. 8, the diameter of the tunnel is 6 mm.

The radial guides 13 d are three plates lying within planes thatintersect at the axis of the inlet chamber. The outer face of each plate13 d is flush with the lateral outer surface of the upper part 13 c. Thecentral zone of the upper part containing the axis of the inlet chamberis void for passage of the fluid. This central zone constitutes a tunnelhaving a diameter greater than the diameter of the tunnel 13 e.

The upper part 13 c is in the form of a cylinder, having two differentthicknesses, a first thickness on the upstream side, i.e. on the side incontact with the radial guides 13 d, and a second thickness, smallerthan the first, on the downstream side. A step 13 f is located betweenthe two thicknesses. With such an arrangement, an inductor 17 as set outin FIG. 9 can be inserted and fixed to the inside of the inlet chamber13 in the part 13 c of great thickness. During insertion, this inductor17 can be fitted on the ends of the guides 13 d. The dimensions of theinductor 17 are such that once inserted, the upper part thereof is flushwith the step 13 f. Other embodiments can be envisaged, such as forexample a single piece constituted by elements 13 c and 17, or 13 and17. The inductor 17 is a hollow cylinder comprising radial guides 17 a,for example from four to six in number, over the entire height of thecylinder and lying in radial planes converging at the centre of thecylinder. The inductor 17 acts as a fluid intake guide. It makes itpossible to limit cavitation in the upper stages. The guides 17 aproduce a laminar flow such that the turbulent nature of the fluid isreduced considerably. This makes it possible to slow and reducedeterioration of the turbine, which is generally rapid, by limitingrepeated impact of the fluid on the blades of the turbine.

It will be noted that only the upper part 13 c of the inlet chamber canbe combined with the rest of the pump when the casing and the turbineconstitute a brushless motor.

FIG. 10 shows the casing 9 in greater detail, constituted by a main body9 a and a secondary body 9 b. The main body 9 a is an elongatedcylinder, the secondary body being a cylinder the outside diameter ofwhich is less than the outside diameter of the main body. The secondarybody 9 b is shaped so as to be inserted and held fixed within the upperpart 13 c of the inlet chamber.

Preferably, the lower end of the secondary body 9 b abuts the step 13 f,shown in FIG. 8.

The inner shape of the casing 9 is complementary to the outer shape ofthe turbine, with a gap between them. The upper end 9 d of the casing 9comprises an internal diameter greater than the diameter of the lowerpart 9 c; the lower part housing the turbine. The diffuser 14 and thestraightener 15 are housed in this upper part 9 d of the casing 9. Theturbine therefore does not occupy the entire length of the casing. Theturbine can be held in the casing by using bearings and seals.

By means of the specific shape thereof, the turbine according to theinvention allows kinetic energy to be imparted to the fluid. It adjuststhe speed of the fluid without shear, also increasing its pressure. Tothis end, the outlet elements of the pump contribute towards increasingthe pressure by having a small outlet orifice as well as specificshapes.

FIG. 11 shows the diffuser 14 which is a cylinder intended to cap thehead of the turbine. The diffuser comprises guide blades 14 a orientedin the direction of outflow of the fluid driven by the turbine. Theorientation of the guide blades makes it possible to convert a portionof the kinetic energy of the fluid into pressure, which is potentialenergy. The thickness of the guide blades can be stable along thediffuser, or can be variable.

FIG. 12 shows a straightener 15, the purpose of which is to guide theoutflow of the fluid by creating a laminar flow so as to eliminate allturbulence. This is a cylinder 15 a open at its base to receive thefluid originating from the turbine via the diffuser 14. It comprises anorifice 15 b having a smaller diameter with respect to the diameter ofthe opening 15 a on its base.

An inner wall 15 d can be seen, having a concave conical shape from theopening 15 a over its first half, then convex conical over its secondhalf towards the orifice 15 b. The fluid is pressurized when pushedtowards the small-diameter orifice.

Three guide blades 15 c can also be seen, lying within radial planesthat converge at the centre of the straightener. Each blade is a platethe width of which is thicker on the side of the wall than on the sideof the centre of the cylinder. The width then reduces as the distancefrom the wall of the cylinder increases.

In the configuration described, for each guide blade, the profile of theside facing the axis of rotation of the cylinder is curved, inparticular in an arc of circle, such that the guide blades are closer toone another at the level of the orifice and are further away on the sideof the opening 15 a.

The turbine 1 according to the invention, with the casing 9 andelectronic and magnetic elements, forms a brushless motor capable ofmaking the fluid flow.

Another turbine 18 according to the invention is shown in FIG. 13. Thisturbine 18 can be identical to the turbine 1 described above, with orwithout magnetic components (windings and permanent magnets and anyother element allowing a motor to be constituted). When it does notcomprise permanent magnets, the body of the turbine can have a lighterand more slender design.

The particular difference with the turbine 1 is the presence here of atransmission shaft 19 which is fixed to the turbine 18. Thistransmission shaft 19 is inserted into the axis of the turbine 18 andhas a greater length such that it extends beyond the turbine through thelower (upstream) part and does not extend beyond the upper (downstream)end of the turbine. The upper end of the transmission shaft 19 comprisesfour ribs or rods 20, each connected at the end of a blade. As shown inFIG. 15, provision is also made for the transmission shaft to be fixedat the level of the lower (upstream) end of the turbine 18, directly orvia ribs at the lower ends of the blades. In this way, the transmissionshaft is solidly connected to the turbine, the rotation of this shaftcausing the turbine to rotate. This shaft 19 can be the transmissionshaft of an external motor or an independent rod capable of engagingwith a motor.

FIG. 14 is an exploded view in which the same elements are shown as inFIG. 5, but with a turbine 18 replacing the turbine 1. The transmissionshaft passes through the axis of revolution of the inductor 17 and ofthe inlet chamber 13. The casing 9 can also be different, moresimplified, when it has no magnetic windings for constituting a stator.

Control of a turbine 18 and a casing 9 can be envisaged both by anexternal motor via the transmission shaft 19 and by an asynchronous orbrushless motor constituted by the turbine 18 and the casing 9. Itshould be noted that the external motor can also advantageously be thebrushless type.

In FIG. 16, the arrows 21 represent the flow of the fluid such as bloodinside the pump. The blood arrives radially through the openings 13 a ofthe inlet chamber, then is orientated axially along the transmissionshaft 19 via the inductor 17, the transmission shaft being in rotationas well as the turbine 18. The blood is then evacuated via the diffuser14 and the straightener 15.

The blood flow is then evacuated towards the outside, passing throughthe diffuser 14 and the straightener 15 which by means of its outletorifice creates a high-pressure laminar flow. Provision is made for thepump to operate under immersion at a frequency ranging from 500 to10,000 rpm.

FIG. 17 shows a pump according to the invention incorporating theturbine 18 as well as an external brushless motor 22. The latter isfirmly connected to the transmission shaft 19 by means of a drive shaft23. Preferably, this connection is detachable, so that it is possible toreplace the motor easily in the event of failure. This can be aconnection by clip, screwing or other. This connection can also be theonly joint between the motor and the rest of the pump.

FIGS. 18 and 19 show a diagrammatic representation of an individualinductor 24 in FIG. 18 and a diagrammatic representation of the blades25 only of this inductor in FIG. 19. This inductor can be individuallydesigned. It will then be fixed firmly in an inlet chamber. It can alsobe directly produced in an inlet chamber or in a turbine enclosure; inthis case the blades are produced on the inner wall of the inlet chamberor the turbine enclosure. The central zone of the inductor is left freefor the passage of the fluid. In FIG. 19, the central zone of theinductor represents the flow of the fluid.

Generally, and for all of the embodiments, the blades of the inductoraccording to the invention are thicker upstream than downstream in thedirection of displacement of the fluid. The thickness progression can belinear, but preferably discontinuous: a linear progression until acertain thickness is reached, then the thickness remains constant overthe remaining length of the blade. Furthermore, the blades can also bethicker at the point of connection with the cylinder 26 which bears themthan at the central end. Provision is also made for an angle between theradial section of each blade and the radius of the cylinder 26 bearingthe blades.

FIGS. 20 and 21 show a front view and a rear view of a straighteneraccording to the invention. This straightener can be producedindividually then fixed in the casing of the pump or directly producedon the inner wall of the casing, i.e. a wall shaped identically to theinner wall of the cylinder 27 of the straightener and the bladesdesigned directly on this wall. The blades 28 are thicker upstream thandownstream in the direction of flow of the fluid. The thicknessprogression can be linear. FIG. 20 shows the downstream side of thestraightener, i.e. the point through which the fluid is outlet. FIG. 21shows the upstream side of the straightener, the fluid inlet. On thislatter side, the blades 28 leave a central space larger than that of thedownstream side, the blades and the inner wall 29 of the cylinder 27bearing the blades being designed so as to guide the fluid to the outletorifice 30 which is narrower than the inlet of the straightener.

Of course, the invention is not limited to the examples which have justbeen described and numerous modifications may be made to these exampleswithout departing from the scope of the invention.

The pump according to the invention can easily be implanted in a heartdue to its small dimensions, on account of its particular designallowing high pressure while preserving the quality of the blood.

The pump according to the invention has a low consumption due to itsoperation in accordance with the physiological heartbeat: an oscillatingflow.

The pump according to the invention operates by propulsion: the rhythmis pulsed.

The pump according to the invention makes it possible to limit thesurface of contact with the fluid as well as the flow resistance of theturbine. Shear stress on the blood cells is also limited.

With a hollow turbine according to the invention, there is aconsiderable weight saving, which limits the energy necessary foroperation thereof. This also makes it possible to increase the passingflow volume as well as the flow rate.

These advantageous characteristics make it possible to improve theoverall comfort of any patient fitted with such a pump.

Provision is advantageously made for the pump according to the inventionto operate in a vertical position; with the rotor being arrangedvertically, the fluid enters via the inductor, passes through the rotor,and is then outlet at the top via the diffuser and the straightener.Most of the pumps of the prior art operate in a horizontal position. Theinlet and outflow capacity allows the pump according to the invention tooperate in a vertical position. Such a pump, placed in a left or rightventricle for example, has the advantage of having an inlet and anoutlet directly in this ventricle. This makes it possible to avoid thepresence of an inlet and/or outlet tube as exists on other devices ofthe prior art.

1.-22. (canceled)
 23. A turbine for a fluid pump, comprising: a body designed to perform rotational movements; a hollow central part passing right through the body and intended for the passage of fluid through the turbine; at least one vane arranged on the inner wall of the body, in the hollow central part, and designed to cause the fluid to flow; and a rod arranged along the central axis of the turbine so as to reduce the backflows of fluid, said rod being fixed to one of said at least one vane, to the body of the turbine and by one end to an inlet chamber.
 24. The turbine according to claim 23, characterized in that the vane is of a helical type.
 25. The turbine according to claim 23, characterized in that it comprises several vanes distributed over the inner wall of said body.
 26. The turbine according to claim 23, characterized in that the vane is constituted by several turns with an increasing winding pitch that tends towards infinity
 27. The turbine according to claim 23, characterized in that the hollow central part of the turbine has a cylindrical shape.
 28. Turbine according to claim 23, characterized in that the hollow central part has a flared shape, the more open end being arranged downstream in the direction of flow of the fluid.
 29. The turbine according to claim 23, characterized in that the hollow central part of the turbine has an oblong shape, the more open end being arranged downstream in the direction of flow of the fluid.
 30. The turbine according to claim 23, characterized in that said body has an outer shape of the right cylinder type with a circular cross section.
 31. The turbine according to claim 23, characterized in that permanent magnets are incorporated in said body.
 32. The turbine according to claim 23, characterized in that the radial thickness of the vane is fixed or variable over the entire length between the upstream end and the downstream end of this vane.
 33. The turbine according to claim 23, characterized in that the hollow central part and said at least one vane have a profile of centrifugal type on the upstream side, mixed-flow type in the central part, and axial type on the downstream side.
 34. The turbine according to claim 33, characterized in that a first zone of said at least one vane is dimensioned so that the fluid reaches a specific speed comprised between 0 and 1.2; this first zone being on the upstream side of the vane.
 35. The turbine according to claim 33, characterized in that a second zone of said at least one vane is dimensioned so that the fluid reaches a specific speed comprised between 1 and 2.2; this second zone being at the level of the middle of the vane.
 36. The turbine according to claim 33, characterized in that a third zone of said at least one vane is dimensioned so that the fluid can reach a specific speed greater than 2.2; this second zone being on the downstream side of the vane.
 37. A pump designed for the circulation of a fluid, said pump comprising: a casing; a turbine arranged in the casing and designed to perform rotational movements relative to the casing; the turbine comprising: a body designed to perform rotational movements; a hollow central part, passing right through the body and intended for the passage of fluid through the turbine; at least one vane arranged on the inner wall of the body, in the hollow central part, and designed to cause the fluid to flow; a rod arranged along the central axis of the turbine so as to reduce the backflows of fluid, said rod being fixed to one of said at least one vane, to the body of the turbine and by one end to an inlet chamber.
 38. The pump according to claim 37, characterized in that the casing and the turbine constitute a part of a brushless motor, the casing having the stator function and the turbine having the rotor function.
 39. The pump according to claim 37, characterized in that the casing has stator windings and the turbine comprises permanent magnets.
 40. The pump according to claim 37, characterized in that it comprises a motor external to the turbine and driving the rod which acts as a transmission shaft, the latter being arranged along the axis of rotation of the turbine and solidly connected to the turbine by at least one radial rib.
 41. The pump according to claim 40, characterized in that the transmission shaft is connected at the upstream end and at the downstream end of the vane.
 42. The pump according to claim 37, characterized in that it also comprises: an inductor equipped with guide blades to make the flow of the fluid linear; this inductor being arranged upstream of the turbine with respect to the direction of flow of the fluid; a diffuser equipped with diffusion blades in order to make the flow of fluid linear and increase the pressure of the fluid; this diffuser being arranged downstream of the turbine so as to evacuate the fluid outwards from the turbine, converting the kinetic energy created by the turbine into potential energy; and a straightener equipped with straightener blades and an outlet orifice having a diameter less than the inlet diameter of the straightener, the straightener blades directing the fluid from the diffuser to the orifice so as to increase the speed and give the fluid a predefined profile when leaving the orifice.
 43. The pump according to claim 42, characterized in that it comprises in addition an inlet chamber provided with side openings so that the fluid can enter radially then engage axially towards the inductor.
 44. The pump according to claim 43, characterized in that the inlet chamber has a cylindrical shape comprising, on its upper part downstream of said openings, a receptacle for housing the inductor. 